The commissioner shall have the power to appoint an assistant, who shall be deputy commissioner of public lands with power to perform any act or duty relating to the office of the commissioner, and, in case of vacancy by death or resignation of the commissioner, shall perform the duties of the office until the vacancy is filled, and shall act as chief clerk in the office of the commissioner, and, before performing any duties, shall take, subscribe, and file in the office of the secretary of state the oath of office required by law of state officers.